In regard to a method of producing an alloy ribbon by jetting an alloy melt of a rare earth magnet material on a single metallic roll, Japanese Examined Patent Publication No. 3-52528 discloses in line 30 of column 7 on page 4 to line 42 of column 9 on page 5 that an alloy ingot sample is placed in a quartz tube and melted, and then the melt is jetted at a constant speed on a metallic disk having too high heat capacity for the melt through a circular orifice provided in the lower portion of the quartz tube to obtain an alloy ribbon. Japanese Unexamined Patent Publication No. 59-64739 reports that for a rare earth-transition metal-B system magnet composition, the rotational speed of a roll is an important factor which influences the magnetic properties of an alloy ribbon.
However, consideration has not been given to how the detailed dimensions, shape and surface state of an alloy ribbon affect magnetic properties.
In addition, a permanent magnet material produced by a conventional rapid cooling method has the following problems.
1) Magnetic properties deteriorate due to variations in the micro structure which constitutes the alloy ribbon.
2) In the formation of a bonded magnet, when a resin is nonuniformly adhered to a magnet powder, reliability, particularly corrosion resistance, deteriorates.